Having completed the isolation of a parotid hormone from porcine parotid glands, we want to isolate from porcine hypothalami the releasing factor (paratid hormone releasing factor, PH-RF) which stimulates the secretion of PH and also demonstrate the biologic specificity of PH-RF to stimulate the secretion of PH. The methodology for the isolation of PH-RF will parallel the methodology developed for the isolation of TRH, LRH, and somatostatin. The PH-RF activity will be extracted from acetone-dried hypothalamic powder and will be purified sequentially with the following steps: (1) ultrafiltration; (2) column chromatography utilizing both gel and adsorptive cellulose; (3) electrophoresis involving isoelectric focusing, analytical and preparative polyacrylamide gel electrophoresis; and, (4) partition chromatography. The long-term significance of this research proposal is to provide additional evidence that systemic factors are important determinants in whether teeth will or will not decay.